The generic devices are used, in particular, when a container is supplied with an air flow from the outside. The object is to prevent moisture from infiltrating the container. Such a container can contain, for example, hydraulic oil for supplying a hydraulic system. The infiltration of moisture into the container can lead to a reduction in power or even damage to the attached system. To supply an air flow from the outside, the generic devices have an inlet device, so that, for example, when the level of a medium that is introduced into the container drops, air from the outside can be fed into the container by the device. The medium in the container can decrease, for example, by removal of the medium. In the reverse case—that is, the level of the medium in the container rises and consequently the air flow must be removed from the container to the exterior—the generic devices often have an outlet device, in addition to the inlet device.
Typically, such drying devices use drying agents, which, however, taken by themselves, are only intended to cover one specific area of a preferred application, in particular, as a function of the moisture situation, temperature, and composition of the medium flow to be dried. Therefore, it is necessary to select from the prior art a drying agent that is the most appropriate for the field of application in order to attain the intended effect.
In this respect, DE 100 31 004 B4 discloses a device for ventilating containers that hold air that has been dried by adsorption. In this case, aluminum oxide is introduced into the container as the adsorbing agent. Then the air is fed from the outside through the adsorbing agent into a container which is to be attached, from which an air removal to the exterior is also possible. The arrangement of a plurality of non-return valves ensures in the solution known from the prior art that the container with the moisture adsorbing agent is charged with air only when the air is actively supplied and not when the air is actively removed. In particular, if the attached container contains hydraulic oil, the efficiency of the adsorbing agent would be reduced if it were traversed by oil vapors of the removed air.
EP 0 135 006 A2 also discloses a device for ventilating with dried air. In this case, a silica gel is the drying agent that is introduced into a container supplied with air from the outside by way of a dust filter. After this air has passed through the drying agent, it is fed to a medium conductor, which communicates with the attached container.